On Sunday, he told CTV's Question Period that aboriginal groups conducted a study in 2005 which concluded the proposed twin pipeline's potential environmental risks outweighed its benefits.

Not all First Nations groups, however, have vetoed the project. Some have inked deals with Enbridge for a financial stake.

In Kathryn Marshall's eyes, it's a fair business deal. As a spokesperson for EthicalOil.org, she argues that opposing Northern Gateway could push oil production to countries with looser environmental standards.

"If you care about ethics then support places like Canada that have environmental laws, have human rights protections, have workers rights protections," she said.

She said the project would allow Canada to export to countries who could, in turn, reduce their dependency on so-called conflict oil.

But Eric Swanson of Dogwood Initiative, which opposes oil tankers on the West Coast, said the project poses both domestic and international threats.

He takes issue with the proposed pipeline shipping Alberta bitumen through First Nations land and onto supertankers, which he said are "bigger than the Exxon Valdez."

Speaking from a Victoria studio, he warned of a potential environmental disaster.

"We don't think that's in Canada's best interests and I'm wondering what is ethical about that," he said in a veiled jab at Marshall's comments.

The Northern Gateway twin pipeline has been called the largest private infrastructure project in B.C.'s history.